Principal David Hunter said the school's roll was 1037 in 2018, but it was expected to reach 1150 in 2019 - its largest roll on record.
He said much of that growth was being driven by the increasing number of junior pupils coming into the school, and that in turn was driven by significant growth in the Mosgiel-Taieri population.
"We will be at capacity in 2019."
The school already had an enrolment zone in place for year 7 pupils, and it was being used to control the growing numbers of junior pupils wanting to enrol.
Last year, Mr Hunter said no year 7 pupils were taken from outside the school's enrolment zone, and the situation was continuing for 2019.
Logan Park High School co-principal Kristan Mouat said she was expecting a 30% increase in year 9 pupils for 2019 which would push the overall roll to more than 650 pupils - the highest it has been since 2006.
Ms Mouat said the growth meant the school would be employing up to four new teachers across varying levels, to accommodate the growing class sizes.
Kaikorai Valley College principal Rick Geerlofs said he, too, was expecting growth in his junior roll in 2019.
He said figures to date showed there had been a 10% increase in year 7 pupils enrolling for the 2019 year.
The school also experienced significant growth in its junior roll in 2018, when more than 100 new pupils enrolled at the school.
At the time, he said it was the largest intake since 2008 and he was absolutely thrilled the growth was continuing in to 2019.
He believed it was a vote of confidence in the school from the community and contributing schools.
While some other Dunedin secondary schools were predicting a minor decrease or slight increase in their junior rolls for 2019, most said their junior intake would be similar to previous years.
The stability of the intakes bodes well for Dunedin's declining secondary school rolls.
They had dropped from 7621 in 2008 to 6773 in 2017.
But with primary school rolls increasing from 5105 in 2008 to 6003 in 2018, the secondary rolls increased for the first time in more than a decade, to 6775 in 2018.
